Pyrometer



Nov. 5, 1935.

PorE/v T/OMETER LEADS C. H. A. F. L. ROSS PYROMETER Filed June 19, 1931POTENTIO- METER In wen/for: C'harlea IZJZKL.ROJJ,-

Patented Nov. 5, 1935 UNITED STATES PATENT OFFlCE- 8 Claims.

This invention relates generally to pyrometers or instruments for themeasurement of high temperatures. More specifically, it relates to sucha device of the thermocouple type, and of particular use in themeasurement of the temperature of a bath of molten metal.

A major object of the present invention isthe provision of a novel typeof thermo-couple.

A further object of the invention is the provision of novel protectivematerial of particular utility in conjunction with thermo-couples.

A still further object of the invention is the arrangement of suchprotective material on the thermo-couple so as to give maximumprotection with minimum interference with the heat transfer to thethermo-couple junction.

With these and other objects in .view, which may be incident to myimprovements, the invention consists in the parts and combinations to behereinafter set forth and claimed, with the understanding that the:several necessary elements comprising my invention may be varied in,construction, proportions and-arrangement.

without departing from the spirit of the invention and the scope of theappended claims.

In order to make my invention more clearly understood, I have shown inthe accompanying drawing, means for carrying the same into practicaleflect without limiting the improvements in their useful applications tothe particular constructions which, for the purpose of explanation, havebeen made the subject of illustration.

In the drawing:

Figure 1 is a view, partially in section, of a thermo-couple embodyingthe invention.

Figure 2 is a somewhat diagrammatic view showing the electricalconnections of the thermocouple.

Figure 3 is alongitudinal sectional view of the end of the thermo-coupleand taken on line 3-3 of Figure 1.

Figure 4 is a transverse sectional View of the end of the thermo-coupletaken on line 4-4 of Figure l.

- The thermo-couple, per' se, consists of two wires of dissimilar metalswhich are shown most clearly in Figure 3. These consist of a wire i, ofpure platinum, and a wire, 2, of 90% platinum and 10% rhodium. The wireslie in the parallel The upper end of the hollow carbon rod 6 is bores ofa porcelain protection tube, 3, and are clamped between two L-shapedmembers, 1, which are held together by suitable bolts, 8. Also clampedbetween such members 1, as shown in Figure 1, is a rod, 9. This rod, asindicated,

is hollow for a portion of its length, and the'wires I l and 2,protec'tedby short segments of tubing, 3', similar to tube 3, are ledthrough this hollow portion after leaving the top of the hollow car bonrod 6. After passing about half way along the rod, the wires are broughtout at the top 10 of the rod and the short protective segments arediscontinued.

To protect the carbon rod 6 from the action of thevfumace, it issurrounded with laminated asbestos, III, which has been saturated with a5 thick solution of sodium silicate. In practice, the asbestos sheet isthoroughly impregnated. with the solution, Wrapped about the carbon rod6 while it is still moist and allowed to dry in its final position. Thelaminated asbestos is se- 20 curely held in position by being bound bynichrome'wire, ii.

It will be noticed that this binding consists of groups of coils, l2,spaced at intervals over which a more open lattice of wire, I3, iswound. 2B The groups of coils, [2, strongly bind the laminatedmaterialto the rod 6, while the more open lattices l3 prevent the detachment ofportions of the material.

It will be noted that the laminated asbestos 30 coating is not extendedto the very end of the carbon rod 6, but that this lower extremity,which is to be inserted in the molten metal, is left uncovered. It'hasbeen found that it is not the molten metal which destroys the rod, but35 the action of the furnace. Accordingly, by having the portion of therod which is inserted in the metal uncovered, a material advantage isobtained since the heat penetrates more easily to the thermo-junction,and none of the protective 40 features are lost.

The remaining portions of the thermo-couple are protected by a wrappingof asbestos rope, which has been impregnated with a thick solution ofsodium silicate. It will be noted that a fairly large rope, H, has beenused to cover the thermo couple from the part of rod 9 where the wiresemerge down to the upper part of the laminated asbestos, which itoverlaps. The outer end of the rod 9 is coveredwith wrappings 'of asmaller rope, l5, which also acts as a protective covering for the wiresI and 2 which lie above the rod at that part thereof.

The. wires l and 2 are suitably connected to a potentiometer, asindicated in Figure 2, and the u tective coating may be of asbestosimpregnated with sodium silicate, and the remaining part, of French sandand sodium silicate.

While I have shown and described the preferred embodiment of myinvention, I wish it to be understood that I do not confine myself tothe precise details of construction herein set .forth, by way ofillustration, as it is apparent that many changes and. variations may bemade therein, by those skilled in the art, without departing from thespirit of the invention or exceeding the scope of the appended claims.

I claim:

1. A protective casing for a thermo-couple com prising a hollow carbonmember adapted to be inserted in molten metal, and a protective coatingthereon in the zone of hot gases existing above the surface of themolten metal to prevent oxidation of such member, said coatingterminating short of the extremity of the member that is immersed in themolten metal.

2. A protective casing for a thermo-couple comprising a hollow carbonmember adapted to be partially immersed in molten metal, and aprotective covering thereon for such part of the surface of the carbonmember as is not to be immersed, said coating terminating short of theextremity of the portion of the member that is immersed in the moltenmetal.

3. A protective casing for a thermo-couple comprising a hollow carbonmember and a covering therefor of laminated asbestos impregnated withsodium silicate.

4. A protective casing for a thermo-couple comprising a hollow carbonmember adapted to be partially immersed in molten metal, and aprotective covering of laminated asbestos impregnated with sodiumsilicate for such part of the member as is not to be immersed.

5. A protective casing for a thermo-couple comprising a hollow carbonmember, a covering therefor of laminated asbestos impregnated withsodium silicate, and a wire binding of nichrome to maintainthe'covering-on the member.

6. A protective casing for a thermocouple comprising a hollow carbonmember and a covering therefor of a non-inflammable porous materialimpregnated with sodium silicate.

7. A protective casing for a thermo-couple comprising a hollow carbonmember, a covering therefor of asbestos impregnated with sodiumsilicate, and means to maintain the covering on the memher.

8. A protective casing for a. thermo-couple comprising a hollow carbonmember adapted to be partially immersed in molten metal, and aprotective covering of asbestos impregnated with sodiuni silicate forsuch part of the member as is not to be immersed.

CHARLES H. A. F. L. ROSS.

